如何使用Qt中的QGeopath清除Mappolyline

How to clear Mappolyline using QGeopath in Qt

本文关键字：清除 Mappolyline QGeopath 中的 何使用 Qt      更新时间：2023-10-16

我使用c++中的QGeopath和Pathcontroller类绘制mapPolyline。现在我要清除该映射多段线。我正在使用Qgeopath类中的clearPath((函数，并在按钮的onclicked上调用它。如何从c++/qt中清除路径。我试过这个代码

路径控制器.h

class PathController: public QObject{
Q_OBJECT
Q_PROPERTY(QGeoPath geopath READ geoPath WRITE setGeoPath NOTIFY geopathChanged)
public:
PathController(QObject *parent = 0) : QObject(parent) {}
QGeoPath geoPath() const {
return mGeoPath;
}
void setGeoPath(const QGeoPath &geoPath) {
if(geoPath != mGeoPath) {
mGeoPath = geoPath;
emit geopathChanged();
}
}

Q_INVOKABLE void clearPath(){
mGeoPath.clearPath();
}
signals:
void geopathChanged();
private:
QGeoPath mGeoPath;
};

main.cpp

int main(int argc, char *argv[]) {
QGuiApplication app(argc, argv);
QGeoPath path;
// path.addCoordinate(QGeoCoordinate(55.006355, 92.860984));
path.addCoordinate(QGeoCoordinate(55.1, 93.4567));
path.addCoordinate(QGeoCoordinate(56.1, 92.777));
PathController controller;
controller.setGeoPath(path);
// path.clearPath();

QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("pathController", &controller);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec();
}

main.qml

Window {
visible: true
width: 640
height: 480

Plugin{
id: osmMapPlugin
name: "here"
PluginParameter { name: "here.app_id"; value: "oBB4FivcP23m2UZQCj8K" 
}
PluginParameter { name: "here.token"; value: "P-D8XRRGeVt0YphUuOImeA" 
}
}
Map {
anchors.fill: parent
plugin: osmMapPlugin
center: QtPositioning.coordinate(56.006355, 92.860984)
zoomLevel: 10
MapPolyline {
id: pl
line.width: 10
line.color: 'green'
}
Button {
id: button
x: 78
y: 117
text: qsTr("clear")
onClicked: {
pathController.clearPath();
}
}
}
function loadPath(){
var lines = []
for(var i=0; i < pathController.geopath.size(); i++){
lines[i] = pathController.geopath.coordinateAt(i)
}
return lines;
}
Connections{
target: pathController
onGeopathChanged: pl.path = loadPath()
}
Component.onCompleted: pl.path = loadPath()
}

然而，我在地图上得到了一条多段线。地图多段线不清除。问题-如何清除地图多段线

您似乎在使用我之前的答案，当前mGeoPath并不意味着QML将被通知，要通知QML，您必须发出geopathChanged信号：

Q_INVOKABLE void clearPath(){
mGeoPath.clearPath();
emit geopathChanged();
}
mapPolyline.path = []

这可以清除qml中的整条线。

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